Logging disturbance shifts net primary productivity and its allocation in Bornean tropical forests

• Published in: Global change biology Vol. 24; no. 7; pp. 2913 - 2928
• Main Authors: Riutta, Terhi, Malhi, Yadvinder, Kho, Lip Khoon, Marthews, Toby R., Huaraca Huasco, Walter, Khoo, MinSheng, Tan, Sylvester, Turner, Edgar, Reynolds, Glen, Both, Sabine, Burslem, David F.R.P., Teh, Yit Arn, Vairappan, Charles S., Majalap, Noreen, Ewers, Robert M.
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.07.2018
• Subjects: allocation; Biosphere; Borneo; Canopies; Canopy; Canopy gaps; Carbon; Carbon Cycle; Conservation of Natural Resources; ecosystems; fine roots; forest stands; Forestry; Forests; Global Ecosystems Monitoring; Growth; land use; Logging; Net Primary Productivity; old-growth forests; Primary production; primary productivity; Productivity; SAFE Project; secondary forests; Species; stand basal area; Stand structure; tree census; trees; Trees - growth & development; Tropical Climate; Tropical forests; Wood; Borneo; Global Ecosystems Monitoring; tree census; allocation; net primary productivity; land use; carbon; SAFE Project; logging
• ISSN: 1354-1013; 1365-2486; 1365-2486
• DOI: 10.1111/gcb.14068

Tropical forests play a major role in the carbon cycle of the terrestrial biosphere. Recent field studies have provided detailed descriptions of the carbon cycle of mature tropical forests, but logged or secondary forests have received much less attention. Here, we report the first measures of total net primary productivity (NPP) and its allocation along a disturbance gradient from old‐growth forests to moderately and heavily logged forests in Malaysian Borneo. We measured the main NPP components (woody, fine root and canopy NPP) in old‐growth (n = 6) and logged (n = 5) 1 ha forest plots. Overall, the total NPP did not differ between old‐growth and logged forest (13.5 ± 0.5 and 15.7 ± 1.5 Mg C ha−1 year−1 respectively). However, logged forests allocated significantly higher fraction into woody NPP at the expense of the canopy NPP (42% and 48% into woody and canopy NPP, respectively, in old‐growth forest vs 66% and 23% in logged forest). When controlling for local stand structure, NPP in logged forest stands was 41% higher, and woody NPP was 150% higher than in old‐growth stands with similar basal area, but this was offset by structure effects (higher gap frequency and absence of large trees in logged forest). This pattern was not driven by species turnover: the average woody NPP of all species groups within logged forest (pioneers, nonpioneers, species unique to logged plots and species shared with old‐growth plots) was similar. Hence, below a threshold of very heavy disturbance, logged forests can exhibit higher NPP and higher allocation to wood; such shifts in carbon cycling persist for decades after the logging event. Given that the majority of tropical forest biome has experienced some degree of logging, our results demonstrate that logging can cause substantial shifts in carbon production and allocation in tropical forests. We quantified total net primary productivity (NPP) in tropical logged and old‐growth forest plots in Malaysian Borneo. When stand structure is similar (basal area used as an indicator), logged forests have higher NPP than old‐growth forests. However, logged forests have large gaps with low basal area and low NPP, while they lack the biggest trees and highest basal areas. Therefore, at 1 ha plot scale (n = 5 for logged, n = 6 for old‐growth), NPP does not differ between the two forest types. Each data point and tree stand example is a 20 m × 20 m subplot.